This project will explore the application of a dual-secondary column comprehensive two-dimensional gas chromatograph (GC x 2GC) to characterize and quantitate exposure to toxic chemicals. GC x 2GC provides high resolution, high sensitivity, and short analysis times for a fraction of the cost of gas chromatography/mass spectrometry techniques. In Phase I, (a) a working GC x 2GC prototype will be constructed and characterized, (b) a retention database will be developed to allow peaks to be identified under a wide range of chromatographic conditions, and (c) volatile organic compound profiles of human breath samples from smokers and nonsmokers will be analyzed using the GC x 2GC system. The high-speed and high-resolution of the GC x 2GC instrument allows breath samples to be comprehensively characterized in a few minutes. In Phase II studies, the investigators will (a) employ established animal models to determine if GC x 2GC analysis of breath can detect organ-specific toxicity; (b) use neural/fuzzy algorithms to search for compounds or patterns of compounds indicative of exposure; and (c) characterize the specificity and sensitivity of specific compounds thus identified as markers of toxicity. PROPOSED COMMERCIAL APPLICATION: Although it has been demonstrated that breath analysis can be used to characterize exposure and reaction to toxicants, conventional GC/MS methodology is very expensive and time-consuming. The relatively low cost, high-speed and high-resolution of the novel GC x 2GC instrument under evaluation allows breath samples to be comprehensively characterized in a few minutes. Once fully developed, there is expected to be a significant market for this instrument and for assay services that employ it. This market will include real time ananlysis of air in sites exposure, and parallel monitoring and tracking of exposed individuals.